Integers: 2's complement
	2's complement (2C) may not be intuitively obvious, but it has nice properties
	Negation
		1. flip all bits
		2. add 1 (ignoring any carry out of the msb)
		Example: 11ten is 01011 in 5-bit unsigned binary.  Call this number B.
			1. flip bits:		10100		~B
			2. add 1:		+       1
					10101		-B